Colored incandescent-lamp bulb



Patented Aug 9, 1927.

UNITED STATES .PATENflT OFFICE.

rmnz SKAUPY, or BERLIN,- ennuamr, Assmnon 'ro GENERAL ELECTRIC com rm, 4' conromurxon or mzw xonx.

COLORED INOA NDEBCENT-LAIP BULB.

Application filed April "I, 1925, Serial No. 21,888, and in Germany May 17, 1924.

Colored incandescent lamp bulbs have reviously been produ ed by making the Bulb of colored glass, by providinga bulb of clear glass with a colored coating. either 5 of colored glass, such as is commonly used in the ceramic industry, or of colored varnish. Colored bulbs produced as just described allow the filament to show through more or less and they do not give agood diffusion of light or a good color effect. To overcome the-e disadvantages it'has been proposed to add to the glass which is to be subsequently applied to the bulb of clear glass a clouding medium such as that used in making the opal glazegenerally used in the ceramic industry. However. as colored glazes in thin layers allow a good deal of light to pass, a comparatively thick layer of colored glaze must be used in order to 29 obtain the desired results. The use of thick colored glazes containing a clouding medium is accompanied by great difficulties, because the addition of the clouding medium raises the fusing temperature at which the glazes melt on the bulb, and consequently undesirable cracks and deformations of the bulb are frequently produced. in the very thin walls of the lamp bulb. In addition, the thick glazes, when covering only a part of 39 the bulb, may give rise to undesirable shadows.

The object of the invention is to overcome these defects and in accordance with the in vention the bulb is composed of a translucent glass, such as that commonly known as opal, milk, or mat glass, and a colored glaze, such as that commonly used in the ceramic industry and consisting of a low melting lead borate glass having a melting point lower 40 than that of the bulb glass and containing a suitable pigment, applied to the translucent bulb to cover it, either partly or entirely. In a bulb made in this way the colored coating or glaze serves only to obtain the color efl'ect.-while the uniform diffusion of the light is produced by the translucent bulb itself, which acts as a foundation for the coating or glazes. The colored coating, particularly a glaze, can therefore be applied in a very thin layer. which very greatly reduces the danger of damage to the bulb while the glaze is being fused, particularly if transparent colored glazes are used, because such glazes, as is well known. are more easily feasible than the cloudy gazes,'and, therefore,-

can be burned into the bulb at a lower temperature. By the use of atranslucent foundation the further advantage is obtained that when the bulbis only partly covered'by a colored glaze the covering stands out much more effectively by contrast with the bare white parts of the translucent bulb. Furthermore, where the glaze coating is applied to only parts of the bulb the ap earance of the bulb is not affected. because t e glaze on account of its extreme thinncss does not project appreciably from the bulb.

The invention is illustrated in one form in-the accompanying drawing in which is shown an incandescent lamp bulb provided in accordance with this invention with belts or hands of colored coating or glaze.

provided by the bulb the bands or belts (b) L preferably made of a colored glaze, are applied in the form of layers of veryvslight thickness. I

The glaze may be applied to the bulb (a) in any well known manner. For example, the glaze may be powdered. applied to the bulb, and then the powdered bulb heated to a temperature too low to deform the bulb but high enough so that the glaze fuses or is burned into the bulb. It is also possible before fusing or burning in the powdered glaze, to mix it with water, or if desired with alcohol, and thereby produce a paste which may be applied to the bulb by a brush or a squirting device. The methods above described are particularly useful where the bul is to be provided with belts or bands of colored glaze. Where the entire bulb is to be covered with a uniform layer, the glaze may be applied in any of the ways above described or the bulb may be dipped bodily into the paste made of powdered glaze mixed with water or alcohol.

These bulbs are useful fornot only incandescent lamps, but any other lamps having a light source of high intrinsic brillianc-y, such as an arc lamp, and may also be used to advantage for lamps in which the light is produced by a discharge through gas. I

What I claim as new and desire to secure by Letters Patent of the United States. is

1. A lamp bulb of translucent glass having on a part of its surface a thin adherent 3. A lamp bulb of white translucent glass coating of laze having a melting point havlng on it a band of thin vitreous glaze of 1 lower than t at of said glass and difi'ering lower melting point and difierent color than in color from the bulb. said translucent glass.

2. Alamp bulb of whitetranslucent glass In witness whereof, I have hereunto set having on it a thin adherent coating of a my hand this 19th day of March, 1925. vitreous glaze of lower melting point and v I different color than said glass. v FRANZ SKAUPY. 

